[GitHub] [dubbo-go] beiwei30 commented on a change in pull request #708: Ftr: bitmap in router chain

[GitBox <gi...@apache.org>]

beiwei30 commented on a change in pull request #708:
URL: https://github.com/apache/dubbo-go/pull/708#discussion_r476082067



##########
File path: cluster/router/chain/chain.go
##########
@@ -88,6 +104,116 @@ func (c *RouterChain) AddRouters(routers []router.PriorityRouter) {
 	c.routers = newRouters
 }
 
+// SetInvokers receives updated invokers from registry center. If the times of notification exceeds countThreshold and
+// time interval exceeds timeThreshold since last cache update, then notify to update the cache.
+func (c *RouterChain) SetInvokers(invokers []protocol.Invoker) {
+	c.mutex.Lock()
+	c.invokers = invokers
+	c.mutex.Unlock()
+
+	c.count++
+	now := time.Now()
+	if c.count >= countThreshold && now.Sub(c.last) >= timeThreshold {
+		c.last = now
+		c.count = 0
+		go func() {
+			c.notify <- struct{}{}
+		}()
+	}
+}
+
+// loop listens on events to update the address cache when it's necessary, either when it receives notification
+// from address update, or when timeInterval exceeds.
+func (c *RouterChain) loop() {
+	for {
+		ticker := time.NewTicker(timeInterval)
+		select {
+		case <-ticker.C:
+			c.buildCache()
+		case <-c.notify:
+			c.buildCache()
+		}
+	}
+}
+
+// copyRouters make a snapshot copy from RouterChain's router list.
+func (c *RouterChain) copyRouters() []router.PriorityRouter {
+	c.mutex.RLock()
+	defer c.mutex.RUnlock()
+	ret := make([]router.PriorityRouter, 0, len(c.routers))
+	ret = append(ret, c.routers...)
+	return ret
+}
+
+// copyInvokers copies a snapshot of the received invokers.
+func (c *RouterChain) copyInvokers() []protocol.Invoker {
+	c.mutex.RLock()
+	defer c.mutex.RUnlock()
+	if c.invokers == nil || len(c.invokers) == 0 {
+		return nil
+	}
+	ret := make([]protocol.Invoker, 0, len(c.invokers))
+	ret = append(ret, c.invokers...)
+	return ret
+}
+
+// loadCache loads cache from sync.Value to guarantee the visibility
+func (c *RouterChain) loadCache() *InvokerCache {
+	v := c.cache.Load()
+	if v == nil {
+		return nil
+	}
+
+	return v.(*InvokerCache)
+}
+
+// copyInvokerIfNecessary compares chain's invokers copy and cache's invokers copy, to avoid copy as much as possible
+func (c *RouterChain) copyInvokerIfNecessary(cache *InvokerCache) []protocol.Invoker {
+	var invokers []protocol.Invoker
+	if cache != nil {
+		invokers = cache.invokers
+	}
+
+	c.mutex.RLock()
+	defer c.mutex.RUnlock()
+	if isInvokersChanged(invokers, c.invokers) {
+		invokers = c.copyInvokers()
+	}
+	return invokers
+}
+
+// buildCache builds address cache with the new invokers for all poolable routers.
+func (c *RouterChain) buildCache() {
+	origin := c.loadCache()
+	invokers := c.copyInvokerIfNecessary(origin)
+	if invokers == nil || len(invokers) == 0 {
+		return
+	}
+
+	var (
+		mutex sync.Mutex
+		wg    sync.WaitGroup
+	)
+
+	cache := BuildCache(invokers)
+	for _, r := range c.copyRouters() {
+		if p, ok := r.(router.Poolable); ok {
+			wg.Add(1)
+			go func(p router.Poolable) {
+				pool, info := poolRouter(p, origin, invokers)
+				mutex.Lock()
+				defer mutex.Unlock()
+				cache.pools[p.Name()] = pool
+				cache.metadatas[p.Name()] = info
+				wg.Done()

Review comment:
       done.




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